Case presentation:
A 56-years old Qatari male, a known case of type-II diabetes mellitus and hypertension, presented with a five-day history of progressive dyspnea and dizziness. He also had a three-day history of mild hematuria and one episode of minimal non-bloody vomiting. The patient had no recent infection and no exposure to new medications. He is married (non-consanguineous), a smoker (5 cigarettes per day) but non-alcoholic with no history of illicit drug use.
Upon examination, he was vitally stable (afebrile, Blood pressure 136/76 mmHg, heart rate 93 beats per minute) other than an oxygen saturation (SPO2) of 70% on room air. On examination, he had pallor and jaundice. The rest of the physical exam was unremarkable. Arterial blood gas (ABG) analysis revealed SPO2 of 101 %, and a methemoglobin (MetHB) level of 5.6 % [Table 1]. The patient was initiated on supplemental oxygen, but his SPO2 remained low. Because of a high MetHgb level, a provisional diagnosis of methemoglobinemia was made, and he received methylene blue intravenously (IV) 80mg while in the emergency department. A complete blood analysis revealed low hemoglobin (Hgb) of 9.9 gm/dL, secondary to hemolysis [Table 1, Figure 2]. Chest x-ray and electrocardiogram were unremarkable. A urine dipstick analysis did not reveal significant blood or protein.
A repeated Hgb level after 24 hours showed a further drop to 7gm/dL. As he was symptomatic, two units of packed red blood cells (RBC) were transfused. Unexpectedly, his Hgb continued to drop further [Figure 2]. Continued hemolysis was evident, and a detailed history was retaken to identify the cause of hemolysis. The patient revealed an intake of large amounts of fava beans on the day of the starting of his symptoms. He had a history of eating fava beans in small amounts before without experiencing any symptoms. However, this time, the intake was considerably larger (six fava beans containing sandwiches). Because of suspicion of favism induced hemolysis, a G6PD level was sent, which came low [Table 1]. At this point, he was diagnosed with G6PD deficiency, aggravated by the ingestion of a large number of fava beans. His hemolysis was worsened by methylene blue, which was evident by a progressive drop in Hgb.
The patient was kept in the medical ward under close observation. He received a total of 3000 mg of IV Vitamin C in two divided doses. After two days, his SPO2 improved to 100 % on room air, and Hgb improved gradually to 11 gm/dL on the fifth day [Figure 2]. He was discharged as he became asymptomatic on day five with a follow-up in the acute medical assessment clinic.